Devices
Power supply/universal AC adapter, 3 to 12 volts at 1A (1,000 mA). See Figure 2-1. Part number 273-316 from RadioShack, part PH-62092 by Philips, or similar.
Figure 2-1. AC adapters of this general type can supply a variety of voltages, with a range as wide as 3 to 12 volts.
Breadboard suitable for integrated circuits. Quantity: 1. See Figures 2-2 and 2-3. Part 276-002 from RadioShack, model 383-X1000 made by PSP, part 923252-I by 3M, or similar. A breadboard that has screw terminals mounted beside it will be a little easier to use but more expensive than one that does not have terminals.
Figure 2-2. This “breadboard” for quickly constructing electronic circuits has a metal base, and screw terminals for attaching wires from a power supply.
Figure 2-3. A breadboard without screw terminals is almost as convenient, and is cheaper.
Tools
Wire strippers
Ideal model 45-121 wire strippers for 16- to 26-gauge wire, or similar. See Figure 2-4. (The “gauge” of the wire tells you how thick it is. A higher gauge means a thinner wire. In this book, we will mainly be using thin wire of 20- to 24-gauge.)
You may also consider the Kronus Automatic Wire Strippers, part 64-2981 from RadioShack, or GB Automatic Wire Strippers, part SE-92 from Amazon.com. See Figure 2-5.
The Kronus and GB wire strippers are functionally identical. The advantage of their design is that it enables you to strip insulation from a wire with one hand. But they do not work well on really thin wire.
Figure 2-4. To use these wire strippers, insert a piece of insulated wire in the appropriate-sized hole between the jaws, grip the handles, and pull a section of insulation away. See page 45.
Figure 2-5. These automatic wire strippers enable one-handed operation, but are not suitable for very small wire diameters. See page 44.
Supplies
Hookup wire
Solid-conductor, 22-gauge, minimum 25 feet of each color. See Figure 2-6. Part 278-1221 from RadioShack, catalog item 9948T17 from McMaster-Carr, or check eBay for deals.
It’s easy to buy the wrong kind of wire. You need solid-core wire, which has a single conductor inside the plastic insulation, not stranded, which has multiple, thinner conductors. See Figures 2-7 and 2-8. You’re going to be pushing wires into little holes in a “breadboard,” and stranded wire won’t let you do this. You will also have problems if you buy wire thicker than 22-gauge. Remember: the lower the gauge number, the thicker the wire.
For a little extra money, you can buy an assortment of precut sections of wire, with ends stripped and ready for use. Try catalog item JW-140 (jumper wire assortment) from All Electronics or search eBay for “breadboard wire.” See Figure 2-9.
Figure 2-6. Using hookup wire with different colors of plastic insulation will help you to distinguish one wire from another in your circuits.
Patch cords
Patch cords are not strictly necessary but very convenient. You don’t want audio or video patch cords, which have a plug on each end; you want wires with alligator clips on each end, also sometimes referred to as “test leads.” Try catalog item 461-1176-ND from Digi-Key or catalog item MTL-10 from All Electronics. See Figure 2-10.
Figure 2-7. Solid-conductor wire of 22 or 24 gauge is suitable for most of the experiments in this chapter.
Figure 2-8. Stranded is more flexible, but cannot be used easily with breadboards.
Figure 2-9. Precut wires with stripped ends can save a lot of time and trouble—if you don’t mind paying a little extra.
Figure 2-10. Patch cords, sometimes known as test leads, consist of wires preattached to alligator clips. This is another of those little luxuries that reduces the hassle factor in hobby electronics.
Components
Pushbutton
Momentary-on, SPST, sometimes referred to as OFF-(ON) or (ON)-OFF type. Must be PCB- or PC-mount, meaning is extremely small with thin spiky contacts on the bottom. Quantity: 1. See Figure 2-11.
Figure 2-11. The terminals protruding from this tiny pushbutton are spaced 0.2 inches apart, making it ideal for the “breadboard” that you’ll be using.
Examples are part number AB11AP by NKK, part MPA103B04 by Alcoswitch, or part EP11SD1CBE by C&K. If you have a choice, buy the cheapest, as we’re going to switch very low current.
Switches
Toggle switch, single-pole, double-throw (SPDT), sometimes referred to as ON-ON type. Quantity: 2. See Figure 2-12.
Figure 2-12. This relatively large toggle switch made by NKK has screw terminals, which will reduce the inconvenience of attaching it to hookup wire.
Model S302T-RO by NKK is ideal; it has screw terminals that will eliminate the need for alligator clips. Other options are catalog item MTS-4PC from All Electronics or part 275-603 from RadioShack.
We won’t be switching large currents or high voltages, so the exact type of switch is unimportant. However, the terminals on larger-size switches are spaced wider apart, which makes them easier to deal with.
Relays
DPDT, nonlatching, 12v DC. Quantity: 2.
It’s important to get the right kind of relay—one whose configuration matches the pictures I’ll be using. Look for parts FTR-F1CA012V or FTR-F1CD012V by Fujitsu, G2RL-24-DC12 by Omron, or OMI-SH-212D by Tyco. Avoid substitutions.
Potentiometer
1 megohm linear potentiometer, Part number 271-211 from RadioShack, part number 24N-1M-15R-R from Jameco, or similar.
Transistors
NPN transistor, general-purpose, such as 2N2222 by STMicroelectronics, part PN2222 by Fairchild, or part 2N2222 from RadioShack. Quantity: 4. See Figure 2-13.
Figure 2-13. Transistors are commonly sold either in little metal cans or sealed into little lumps of plastic. For our purposes, the packaging makes no difference.
2N6027 programmable unijunction transistor manufactured by On Semiconductor or Motorola. Quantity: 4 (allowing for 2 spares in case of damage).
Capacitors
Electrolytic capacitors, assorted. Must be rated for a minimum of 25 volts and include at least one capacitor of 1,000 μF (microfarads) and two capacitors of 2.2 μF. If you search on eBay, make sure you find electrolytic capacitors. If they’re rated for higher voltages, that’s OK, although they will be physically larger than you need. See Figure 2-14.
Figure 2-14. An assortment of electrolytic capacitors.
Ceramic capacitors, assorted. Make sure you
